Numerous types of heart valve prostheses have been developed for replacing defective heart valves in human patients. One common type of heart valve prosthesis includes a natural tissue heart valve mounted within a stent. The stent generally provides strength and rigidity to the heart valve. Typically, the stent is covered with a textile material, such as Dacron™, which provides a substrate to which the heart valve may be secured. While the stent provides desired rigidity and strength, which inhibits the inward deflection of the stent posts, it also decreases the hemodynamics of the valve. This is because the stent substantially increases the sidewall thickness of the prosthesis, which reduces the size of the flow orifice for a prosthesis having a given outer diameter. The exposed textile covering also tends to abrade cusps of the valve.
In order to overcome the disadvantages associated with the stented heart valve prosthesis, there has been an increasing tendency to form natural tissue heart valve prostheses with no stent. These are called stentless valves. Stentless valves exhibit improved hemodynamics and are less resistant to blood flow. In addition, stentless valves, as compared to stented valves, are more resistant to structural failure because the rigidity of a stent can cause damage to the moving cusps. The improved hemodynamic characteristics of stentless valves can also cause beneficial remodeling of the heart muscle. For example, it has been determined that several months after implantation of a stentless valve in the aortic position, there is a noticeable improvement in the size of a left ventricle.